1. Field of the Invention
The present invention relates to an image pickup apparatus, a control method therefor, and a computer-readable storage medium storing a control program for implementing the method, and in particular to compensation control in taking moving images or still images while varying exposures.
2. Description of the Related Art
In recent years, image pickup apparatuses such as home video cameras and digital still cameras have become into widespread use among the general public. As image pickup devices used for the image pickup apparatuses, CMOS image pickup devices as well as CCD image pickup devices are used. These image pickup devices have been increasing in the number of pixels so as to meet market's (users') demands. With an increase in the number of pixels of the image pickup devices, the problem of noise generation caused by the image pickup devices themselves have been arising, and accordingly, various methods to reduce or compensate for noise have been proposed.
For example, there has been an image pickup apparatus which performs cyclic processing to compensate for or reduces noise generated during video shooting (see Japanese Laid-Open Patent Publication (Kokai) No. 2010-245998).
On the other hand, there has been known so-called shooting with expanded dynamic range (HDR shooting) which performs shooting with a dynamic range higher than a dynamic range of an image pickup device.
For example, there has been a method which expands dynamic range by synthesizing a so-called underexposed image and a so-called overexposed image together in an image pickup apparatus (see Japanese Laid-Open Patent Publication (Kokai) No. H06-273354). This HDR processing enables shooting with a dynamic range higher than a dynamic range of an image pickup device.
According to the noise compensation method described above, however, no consideration is given to a process in which exposures are purposefully changed like HDR shooting.